                (a) Field of the invention        
The present invention relates to an improved structure of a socket and in particular to a socket which allows the prongs of a plug to trigger the pressing device of the socket to press downward and in turn to fasten or secure the prongs of the plug such that the prongs will not be dislocated from the socket.                b) Description of the prior art        
The purpose of a connection between a socket and a plug is to provide an extension of current supply from a source.
In the currently available sockets, the stability of these sockets depends on the clipping force of the conductive elements within the socket. As such, when the sockets have been used for a long time or the size of the prongs of a socket is not accurate with respect to the insertion holes of the socket, the retention or the clipping force of the conductive elements becomes weak or loose. In such case, when the socket or the plug of an electrical appliance is accidentally touched, the plug may dislocate or fall off from the socket and thus, an interruption of current supply is occurred. To solve this problem, most of the people may widen or narrow the distance in between the two prongs of the plug so as to fix the prongs to the socket. By the adjust t of the distance of the prongs to be inserted into the socket, the clipping of the prongs maybe improved. However, in actual practice, such adjustment does not improved the stability or the mounting capability of the socket. This is because the prongs are normally rigidly fixed to the plug structure and are not flexible. The prongs are not easily extended and if they are extended with great force, the rigidly fixed ends of the prongs within the plug may be damaged. This way of adjusting the clipping ability of the plug to fit the socket is not feasible. Another way to solve this problem is to change the insertion holes of a socket But, in actual practice, this method is not possible as the clipping force of a socket is greatly depending on the elasticity of the conductive elements of the socket With regard to the sent supply to computers, where the cent supply cannot be interrupted, unexpected current interruption often causes a great loss to the users.
Therefore, it is an object of the present invention to design a socket with improved structure, which provides sewed retention of the prongs of a plug at the socket.